How To Use FreeCAD FEM |JOKO ENGINEERING|

and welcome to this video where I'd like to go over how to do an analysis on this table this table is actually created by call visuals for you it's a great channel if you haven't seen them already I work with them quite a bit now well visuals for you actually has a video on how to make this table so it'd be kind of fun to make the table with all visuals for you and then follow along with me if you'd like when we do an analysis so doing an analysis and freecad I find for you can to be a really amazing software the first thing I want to point out is this table is made of multiple bodies right up tabletop or a cap to frame so there's a number of bodies here and analysis my mesh I want to mesh them all up into one body so do that I highlight everything here and on the Start menu I go to part and I choose Union and it creates fusion of all of these bodies notice we have a minor graphic change here I think one of the easy ways to deal with this is I can right click on fusion and change the appearance to something different maybe something like aluminum or something and and it kind of evens out our graphics I mean we've got kind of a beautiful model now I click on fusion and it highlights the entire body and that's what we want all bodies fused into one because then we can mesh it so once we're meshed together let's head on over to something like the FE M menu and we'll click on a for a new analysis one of the other points for analysis that I want to make is we've got things like these bottom feet here we've got a chamber here we've got a few other elements and the general rule behind fe M is to analyze the most simple part without sacrificing results I'm not gonna do that in this video I'm just going to going to do the whole table but there is an option that if you're getting any kind of meshing errors or something you can get rid of small things like the fill that like the feet and and get good results and maybe minimize any measures they might get keep that in mind so I'll talk about meshing here is a little bit later right now let's think about what we want to keep stationary and I'm going to choose this button right here which acres geometry so I'm gonna choose the bottom feet of this table and I'm going to say that these parts that are green are now glued to the floor I'm going to add them so they will not move but you can see I've got the linker symbol on these faces telling me that these will not move in the analysis right these are anchored to the floor the next thing that I'm going to do is choose this tabletop and I have several options I can do a self weight analysis where I just say how does this hold up under its own weight and that button would be there it is self wait right there but I'm going to choose actually a force acting on geometric gonna do the other thing I can do with the pressure so if you wanted to analyze you know a tank or anything under pressure that's a good option but here I'm going to add a force I'm gonna choose this face reverse the direction so the force is going down into the tabletop and this is a Newton's so I can add something like 16 Newtons and call it good again there's our 60 Newtons the next thing I can do is maybe add a secondary force you know if someone bumps a leg or something this leg is very well supported due to the nature of the frame here and so you think it might be the most vulnerable and kering a torsion force or a twisting round force so I'm going to put a force on this face and we'll do a force probably lighter load it something like 20 let's go 30 Newton's acting on that face here and we'll change the direction to going into that face cool so we've got our forces we've got our anchor geometry I'm going to add a material using this button and we'll do something generic maybe something like C 10 steel and so now we're made out of steel and this whole body and I can add perhaps a mesh and the mesh I click on the fusion so the entire body is highlighted and I choose a G mesh and n mesh is not applicable here we'll go with maximum element size notice if I type in 10 I think it interprets is 10 millimeters and converts it to 0.39 inches I think that's what that's doing there and then I can click apply and notice when I click apply depending on your hardware it could take a while so we get meshing and as I was saying before some of these mesh distortions Harvard the Harvard but rather MIT put out a very interesting paper about mesh distortions and I'm not that great with mesh distortions but they this has something interesting that is angular distortions are very insignificant but isoparametric forces are very significant so be in mind of that when you come across any kind of meshing distortion and as we mesh there's there's our ending mesh and we do have them what appears to be kind of a minor distortion point 9 so we'll click OK again you can remove elements and get better results without a distortion I'm going to hide my geometry and just show my mesh so I'm just looking at what I've meshed from here I'll double click on calculates and right and InP file that's for analysis file and then we can run our analysis after that so while we wait for this thing to do its thing I can maybe tell you a little bit about this mesh if you're not familiar so we've we've done a right over on calculates and we're doing some math here so the idea behind this analysis is I've got a really complex geometry and so basic analysis tools really aren't applicable over a complex geometry because it's too complicated to run basic equations so what this analysis aims to do is it says I can break up this complicated geometry into a bunch of little pieces in this case little triangles and if I put a force on one end of a triangle it's easy to calculate what the forces are on the other end of the triangle and I can propagate those calculations all through the entire material so I've taken a really complex geometry by breaking up into really small pieces that I can simply calculate I can run thousands of simple calculations which will give me over an overall geometry for an overall calculation on what we're trying to to analyze so it's kind of a way of simplifying really complex geometry into basic pieces and that's the meshes job and so when we choose smaller sizes for our mesh we have more little triangles and that ultimately gives us a higher resolution on our analysis and that's where analyzing the most simple model comes into play if I was very serious about this I would remove Solis chambers because they probably don't play a significant role how to remove the feet on the table a few other things and that allows for a more simple mesh less calculation but this is just a quick and dirty to show how fvm works so let's see how much longer looks like our calculus is done we've done in ninety four point seven seconds so I'll close that for now again we're just looking at or better mesh here so I've got this beautiful static results that I've seen to show up so if I double-click on this calculates results I can see that my mesh turns green and I can visualize a few different elements of this Fe M the first thing is I can look at absolute displacement and so you can see our mesh changes color displacement is when something moves right I put a load on this face and it doesn't uniformly move but the least supported places move the most and so our red areas are where our frame isn't the least supported places move and I can even visualize how this displaces and again freecad is absolutely brilliant for being this wonderful open-source software I can click on the show box and as I drag this bar it shows me how this table would displace I can I can visualize it although I'm not seeing much displacement as I'm used to seeing but yeah you can see how this table deflects sometimes you see a lot more displacement than than what we're seeing and that's because it exaggerated the displacement so you can visualize it better so if your table is tripping way down that's pretty normal I'm gonna actually make this factor of a thousand so hopefully you'll be able to yeah there's some more distortion so you can visualize a little bit easier this is of course not true maybe I'll go ten thousand so you can see how this buckles in a very predictable way the legs move because of this force on the side and we have a higher distortion and the places that aren't supported and so this table doesn't distort over places that are supported as we would expect so that's that's truly brilliant is showing us exactly what we think of there let's go to von Mises stress this is one of the most important aspects of analysis because one Mises stress is so significant we can see that we are the most stressed right down our frame lines you can you can start to see that and you can even see that the the stress is because of the shear force that's acting between the top of the table and the frame you get that shear force in that table top again as we would expect you also have some stress down at the feet but you can tell the colors are still very green there's not much stress happening here and then you can look at individual displacements like what's the displacement only on my x-axis what's the displacement only on mine Y where my z axes so you have that we have principal stress and shear which of course we've seen so there are some wonderful analysis tools I hope this video was helpful and getting you to start to analyze some things in free canceled again this video is helpful please subscribe and check out all visuals for you and I'll see you in the next video [Music]

Channel: Joko Engineeringhelp

Views: 46,788

Keywords: joko, engineering, help, jokoengineering, engineeringhelp, ACADEMY, jokoengineeringhelp, tutorial, how, to, howto, engineer, JMT, EXPLAIN, EXPLAINED, GOENGINEER, KHAN, FreeCAD, Table, Analyses, FEM, FEA, finite, element, method, analysis, mesh, material, stress, strain, force, pressue, anchor, geometry, calculix, calculation, Blah, von, mises, von mises, shear, torsion, linear, frame, strength, resolution, body, union, unify, fusion

Id: dhrynRdBOIg

Length: 12min 15sec (735 seconds)

Published: Tue Jan 22 2019